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Thread: [Fukushima, power stations, nuclear scare]

  1. #3091
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    Quote Originally Posted by publiusr View Post
    Now this:
    https://www.washingtonpost.com/news/...=.ac1bc6963fcb

    That cave in could have happened in any old tunnel.
    What does a 1950's-era contaminated equipment tunnel collapse have to do with the situation at Fukushima?

  2. #3092
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    Quote Originally Posted by publiusr View Post
    Now this:
    https://www.washingtonpost.com/news/...=.ac1bc6963fcb

    That cave in could have happened in any old tunnel.
    Let me make that official.

    This post has nothing to do with this thread, there is already a thread on this topic, and once again you posted a link with no adequate explanation of what is in the link.
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  3. #3093
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    A new submersible robot will be sent in to flooded areas of Fukushima. Developed by Toshiba and IRID (International Research Institute for Nuclear Decommissioning), it's hoped it will survive where other robots have not.

    http://www.bbc.com/news/in-pictures-40298569
    http://www.design-engineering.com/fu...29-1004026829/
    http://irid.or.jp/en
    Attached Images Attached Images

  4. #3094
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    Japan Pictures Likely Show Melted Fukushima Fuel for First Time
    Apparently this is coming from the submarine like robot geonuc mentioned.
    No doubt, there are better sources than the link I provided.

  5. #3095
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    Quote Originally Posted by Squink View Post
    Japan Pictures Likely Show Melted Fukushima Fuel for First Time
    Apparently this is coming from the submarine like robot geonuc mentioned.
    No doubt, there are better sources than the link I provided.
    That source is as good as any for showing the images. Earlier today, I briefly looked through the usual sources for more complete information but didn't see much. It's a developing story, as they say.

  6. #3096
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    Just a question, but does it make sense to say that this was a smart move? Water is very good at shielding radioactivity, so the dosage the robot receives will be lower than in the air. Or are there radioactive substances in the water that will irradiate the robot?
    As above, so below

  7. #3097
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    Quote Originally Posted by Jens View Post
    Just a question, but does it make sense to say that this was a smart move? Water is very good at shielding radioactivity, so the dosage the robot receives will be lower than in the air. Or are there radioactive substances in the water that will irradiate the robot?
    I wouldn't so much characterize it as a smart move as a necessary move. Much of the reactor will be under water*, so to get a close look, a submersible robot is required.

    As to the radioactivity and shielding, keep in mind that the reactor fuel itself (melted, unmelted) is by far the greatest source of radiation and it is underwater. Water has very good shielding properties as you say, but if what you want to look at is in the water and is the source, the closer you get, the higher the radiation. There is, however, undoubtedly a high concentration of radioactive isotopes in the water too.

    * Edited to add: the robot went into Unit 3, which has a higher water level than Units 1 and 2. In those units, damage to the containment vessels has resulted in much more exposed fuel.
    Last edited by geonuc; 2017-Jul-24 at 01:37 PM. Reason: additional information

  8. #3098
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    Results from muon detectors indicate most of the fuel from the Unit 3 core area is now below the reactor vessel in the primary containment. Previous measurements on Units 1 and 2 yielded similar results, although there is still substantial fuel in the U2 reactor vessel. I find the use of muon detectors for this application somewhat fascinating.

    http://www.world-nuclear-news.org/RS...3-0210174.html

  9. #3099
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    At 42+Sv/hr, is there any plausible mainstream scenario whereby Fukushima could yet have unexpected serious worldwide repercussions, or is this more hype?

    "Report: Massive radiation leak at Fukushima plant — Extremely high levels being detected outside reactor — Officials can’t explain why — Expert warns of global threat: “It’s a disaster of unseen proportions”
    Last edited by wd40; 2018-Feb-08 at 02:03 PM.

  10. #3100
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    Quote Originally Posted by wd40 View Post
    At 42+Sv/hr, is there any plausible mainstream scenario whereby Fukushima could yet have unexpected serious worldwide repercussions, or is this more hype?
    There are so many difficulties with that question "plausible," "unexpected," "serious." I think one answer is that there is no unexpected event that could happen. The problem is that there is a lot of radioactive material there. So the repercussions will come from the leak of radioactive materials into the ocean, which is already happening and will surely continue. But that won't have serious worldwide repercussions. I suppose that if the president of a foreign country visits Fukushima as part of a state visit to Japan, and during the visit trips and knocks his head and ends up dying, that could have unexpected repercussions, but I'm not sure how serious they would be.
    As above, so below

  11. #3101
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    Looks like this is the right thread. Please forgive error, these old ones can be hard to ferret out correctly.
    Robot squeezes suspected nuclear fuel debris in Fukushima reactor.

    So progress continues.

  12. #3102
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    TEPCO announces that they will start removing fuel bundles from the Unit 3 spent fuel pool and transfer them to the onsite fuel storage facility. This work has required first clearing the spent fuel pool floor of debris from the hydrogen explosion. Note that unlike Unit 4, which was defueled at the time of the earthquake/tsunami and thus had hot fuel in the fuel pool, Unit 3 was operating. So the fuel bundles in the pool had been there a while and had already significantly cooled at the time of the event. After eight years, they will be even cooler. The transfer is simply something that must be done eventually to completely decommission the plant.

    Removing the fuel from the three damaged reactor vessels (Units 1,2 and 3) remains a challenge.

  13. #3103
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    Quote Originally Posted by geonuc View Post
    TEPCO announces that they will start removing fuel bundles from the Unit 3 spent fuel pool and transfer them to the onsite fuel storage facility. This work has required first clearing the spent fuel pool floor of debris from the hydrogen explosion. Note that unlike Unit 4, which was defueled at the time of the earthquake/tsunami and thus had hot fuel in the fuel pool, Unit 3 was operating. So the fuel bundles in the pool had been there a while and had already significantly cooled at the time of the event. After eight years, they will be even cooler. The transfer is simply something that must be done eventually to completely decommission the plant.

    Removing the fuel from the three damaged reactor vessels (Units 1,2 and 3) remains a challenge.
    Thanks for the update. Hard to believe it is eight years already...

  14. #3104
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    New video and preliminary analysis from TEPCO reveals an interesting substance found adhered to fuel assemblies in the Unit 3 fuel pool. It's the same stuff previously seen inside primary containment and under the reactor vessel which appears to be the result of interaction of melted fuel (called corium) and concrete. For it to be found in the fuel pool suggests there was a whole lot of corium-concrete interacting going on after the accident, further suggesting that a significant amount of fuel escaped containment after the explosion.

    Lots of photos in this link.

  15. #3105
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    Quote Originally Posted by Strange View Post
    Thanks for the update. Hard to believe it is eight years already...
    Plus 4 more years, accidents take a long time to clean up.

  16. #3106
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    Quote Originally Posted by geonuc View Post
    New video and preliminary analysis from TEPCO reveals an interesting substance found adhered to fuel assemblies in the Unit 3 fuel pool. It's the same stuff previously seen inside primary containment and under the reactor vessel which appears to be the result of interaction of melted fuel (called corium) and concrete. For it to be found in the fuel pool suggests there was a whole lot of corium-concrete interacting going on after the accident, further suggesting that a significant amount of fuel escaped containment after the explosion.

    Lots of photos in this link.
    That seems to be me a very big conclusion based only on the observation that "the stuff looks a bit like pumice" and a comparison of viscous behavior.
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  17. #3107
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    Quote Originally Posted by slang View Post
    That seems to be me a very big conclusion based only on the observation that "the stuff looks a bit like pumice" and a comparison of viscous behavior.
    I don't think anyone has 'concluded' anything.

  18. #3108
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    This video is educational and relevant

    https://www.youtube.com/watch?v=wY3qCKZOF30

    Of great interest is the removal of melted fuel from the cooling system and steam generation areas. This was a minor disaster compared to Fukushima, yet corium was spread all over by travelling through the pipes. There was no explosion, but melted fuel still escaped primary containment.

    There is zero doubt melted fuel escaped from primary containment at Fukushima reactor 3. And secondary containment. Since secondary containment pretty much was blown to little pieces.
    Last edited by Gigabyte; 2019-May-05 at 01:22 PM.

  19. #3109
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    Just for clarity, that's a video on the Three Mile Island cleanup.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  20. #3110
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    Quote Originally Posted by Trebuchet View Post
    Just for clarity, that's a video on the Three Mile Island cleanup.
    Thanks. I wasn't going to watch it.

  21. #3111
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    Quote Originally Posted by Trebuchet View Post
    Just for clarity, that's a video on the Three Mile Island cleanup.
    Took 12 years to cleanup. I don't have an estimate of the Fukushima but it seems likely to be longer since there was an explosion that didn't occur at TMI.

  22. #3112
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    [Fukushima, power stations, nuclear scare]

    Quote Originally Posted by bknight View Post
    Took 12 years to cleanup. I don't have an estimate of the Fukushima but it seems likely to be longer since there was an explosion that didn't occur at TMI.
    Iím not sure exactly but I think the plans are for something like forty or fifty years. A lot is just waiting for radiation levels to fall.


    Sent from my iPhone using Tapatalk
    Last edited by Jens; 2019-May-06 at 07:05 AM.
    As above, so below

  23. #3113
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    Quote Originally Posted by bknight View Post
    Took 12 years to cleanup. I don't have an estimate of the Fukushima but it seems likely to be longer since there was an explosion that didn't occur at TMI.
    The two accidents are not really comparable and not because of the hydrogen explosions at Fukushima, which add a fairly minor complication to the cleanup effort. Minor in comparison to what happened in the primary containments of three reactors.

  24. #3114
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    Quote Originally Posted by geonuc View Post
    The two accidents are not really comparable and not because of the hydrogen explosions at Fukushima, which add a fairly minor complication to the cleanup effort. Minor in comparison to what happened in the primary containments of three reactors.
    I thought I remembered the explosion in the containment, was this not correct?

  25. #3115
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    HBO series on Chernobyl starts tonight. FYI

  26. #3116
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    Quote Originally Posted by publiusr View Post
    HBO series on Chernobyl starts tonight. FYI
    Is the roof caving in still?

  27. #3117
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    Quote Originally Posted by bknight View Post
    Is the roof caving in still?
    They built a dome over the entire thing.

    A giant shield designed to protect the nuclear reactor damaged 30 years ago at Chernobyl has reached its final resting place, completing an unprecedented engineering feat.

    Known as the New Safe Confinement (NSC), the shield will seal off an aging shelter -- built hastily after the disaster occurred in 1986 in what is now northern Ukraine -- that is leaking radioactive material.

    A first for modern engineering, the Chernobyl shield is the largest moveable, land-based structure ever built, according the European Bank for Reconstruction and Development (EBRD), which manages funding for the international project.

    The arch-shaped steel structure was assembled nearby and moved more than 1,000 feet into position with the help of a special skidding system of hydraulic jacks that pushed the mammoth shield one stroke at a time.
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  28. #3118
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    Quote Originally Posted by Swift View Post
    Ah that covers the concrete structure that was crumbling. God for them.

  29. #3119
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    Quote Originally Posted by bknight View Post
    I thought I remembered the explosion in the containment, was this not correct?
    The hydrogen explosions* were in the secondary containment buildings of three reactors. In a BWR, the secondary containment is not a fortified structure. More just a building to house equipment in and provide proper environmental controls. So yeah, the explosions made a mess of the place but the far more significant damage is inside the primary containment structures, which house the reactor vessels and other primary system components.

    * There were three separate explosions at units 1, 3 and 4. Note that unit 4 did not experience a meltdown but it shared a common vent pathway with unit 3. The hydrogen came from unit 3.

  30. #3120
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    Quote Originally Posted by publiusr View Post
    HBO series on Chernobyl starts tonight. FYI
    I watched episode 1 and I'm thoroughly confused by the players, other than there was an explosion and many of the workers are dying and the firemen. Local government wants to shut down city. Bah.

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